UPDATE 3/18/14: We've been waiting and wondering for years about what really happened that night in the Season 1 finale in the bell tower, when Ian Thomas tried to kill Spencer Hastings. And now, we know the truth, as we were promised. So, was Ali the one who pushed Ian to save Spence? Yep! As she revealed in the Season 4 finale, she was, in fact, Spencer's guardian angel that night. Knowing what we do about what happened between Ian and Ali on the night she disappeared, his surprise at seeing her makes even more sense. Are you satisfied now that you know the answer? Tell us below!

ORIGINAL STORY: The mystery of who pushed Ian Thomas off the bell tower has been puzzling Pretty Little Liars fans since the Season 1 finale, and we'll finally learn the truth before the Season 4 spring season is over. However, there's still months between now and then, which means we have plenty of time to speculate about who lent the helping shove and saved Spencer on that memorable night.

Why do we think that Ali might be the one behind Ian's fall? Here are the three biggest reasons.

She seems to be helping the Liars. Ali wasn't always the nicest friend, but since going into hiding she seems to have made it her mission to help the Liars. If all of her mysterious appearances to the girls were not-so-hallucinated after all, then she was definitely leaving them clues and, occasionally, saving their lives. Plus, she pulled them out of the lodge fire. It's not a stretch to imagine her pushing Ian as part of her guardian angel role.

She might have reason to hate Ian. Ali may love the Liars in her own twisted way, but we're not sure if she'd perform random acts of near-murder for them. But Ali and Ian have a history that probably ended on a sour note, which might explain the pusher's apparent lack of hesitation. Ian dying may have played into Ali's plans perfectly.

She could easily have been around. When it comes to figuring out who performed the deed, we need to factor in who was free that night, and who was likely to be following the Liars or Ian (or just hanging out in the church, we suppose, but that seems less likely). Ali obviously had free reign to run around town, thanks to everyone thinking she was six feet under, and we find it very plausible that she was following Spencer (maybe to protect her) or Ian (perhaps she thought he was the one after her?).

Do you think Ali's the one who pushed Ian? Sound off in the comments below!